Lighting controllers are used to control lighting devices in settings that utilize large arrays of lighting equipment. Lighting controllers can control various characteristics of the light emitted from the individual lighting devices. For example, lighting controllers can adjust the intensity and color of the individual lighting devices in a lighting array. It is desirable to adjust the properties of light emitted from non-tungsten-based lighting devices so that the emitted light is adjusted similar to the emitted light of a traditional tungsten-based lighting device.
For example, the correlated color temperature (CCT) property of emitted light indicates the temperature of the color of the light measured in Kelvin. The CCT property can help specify the shade of “white” that is being radiated from a white light source. The CCT property of emitted light helps provide a color tone for the white light in a spectrum of warmth. For example, a light source emitting a white light with a lower CCT value (e.g., below 3200 Kelvin) corresponds to a warmer light (an amber tinged white). A light source emitting a white light with a higher CCT value (e.g., above 6,000 Kelvin) corresponds to a cooler light (a bluish white light). The CCT property of emitted light can also be characterized as the shade of white that is experienced in everyday life. For example, “candlelight” white is typically considered white light around a CCT of 1800 Kelvin. “Household” white light is typically considered white light around a CCT of 2800 Kelvin. And “daylight” white light is typically considered white light around a CCT of 5600 Kelvin.
In traditional tungsten-based lighting units, the CCT is naturally adjusted as the lighting unit increases or decreases in intensity. As a tungsten lighting unit dims, the CCT value of the tungsten lighting unit decreases, resulting in a warmer tone in the overall color gamut. The natural drop in CCT, providing the effect of a warmer color tone, is an artifact of the electrical properties of a black body radiator. Non-tungsten lighting devices, however, do not naturally shift the color nor the color temperature of the produced light when dimming. Examples of non-tungsten lighting devices can include solid state lighting devices, such as light-emitting diodes (LEDs), or gas discharge lighting sources such as arc lamps. It is therefore desirable to automatically adjust the warmth (CCT property) of the light emitted by a lighting unit as the intensity of the lighting device is modified.